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1996 Sources of Air Toxics

THE 1996 EMISSION INVENTORY

As part of the National-Scale Air Toxics Assessment (NATA), USEPA prepared a comprehensive list of air toxics emissions for the entire country in 1996. The emissions inventory for New Jersey was briefly reviewed and revised by NJDEP before being finalized by USEPA. Although there are bound to be some errors in the details of a massive undertaking such as this, a summary of the emissions inventory can give us some indication of what may be the most important sources of air toxic emissions in our state. As can be seen from the pie chart below, Mobile sources are the largest contributors to air toxics emissions in New Jersey, with on-road mobile sources accounting for 35%, and non-road mobile sources contributing 33%. Area sources represent 25% of the inventory (USEPA refers to this category as "Area and Other" because it includes residential, commercial, and small industrial sources). Major Point sources account for the remaining 7% of the inventory. Major Point sources are defined by the Clean Air Act as facilities that emit more than 10 tons per year of a single hazardous air pollutant (HAP) or 25 tons per year of all HAPs combined.

Sources of Air Toxics in New Jersey
Based on U.S.EPA's 1996 Air Toxics Inventory
Sources of Air Toxics in New Jersey
Based on U.S.EPA's 1996 Air Toxics Inventory

USEPA also compiled an air toxics emissions inventory for 1990 as part of its Cumulative Exposure Project (CEP): "An Sab Report: The Cumulative Exposure Project" (Pdf Format) "Modeled Outdoor Concentrations of Hazardous Air Pollutants: Analysis of Data from the Cumulative Exposure Project for the Urban Area Source Program" (Pdf Format). The CEP results were discussed on this website previously, and can still be accessed by clicking here. However, USEPA emphazises that the methods used to conduct the 1990 and 1996 emissions inventories are different, so that the results for the two different years cannot be compared directly.

COMPARISON OF EMISSIONS BY COUNTY

When the emissions estimates are broken down by county, it is evident that the areas with the largest air toxic emissions are generally those with the largest population in the smallest space. This is directly related to high levels of vehicle use, solvent use, and other population-related types of activities in those counties.

Estimated Air Toxics Emissions for New Jersey, by County
Based on U.S.EPA's 1996 Air Toxics Inventory

Estimated Air Toxics Emissions for New Jersey, by County
Based on U.S.EPA's 1996 Air Toxics Inventory

COMPARISON OF EMISSIONS BY SQUARE MILE

The chart below shows the amount of emissions in tons per year per square mile, which is primarily related to population density. Hudson County is the smallest county by area, but by far the most densely populated (12937 people per square mile, compared to the statewide average of 1125 people per square mile).

Estimated Air Toxics Emissions Density for New Jersey, by County
Based on U.S.EPA's 1996 Air Toxics Inventory
Estimated Air Toxics Emissions Density for New Jersey, by County
Based on U.S.EPA's 1996 Air Toxics Inventory

IN NATA, THE POINT, AREA, AND MOBILE SOURCES ARE GROUPED IN THE FOLLOWING WAY:

Major Point Sources: A point source is a stationary facility or process that emits a significant amount of air pollution during manufacturing, power generation, heating, incineration, or other such activity. For NATA, USEPA called this category "Major Sources," and included in it just those sources which emit at least 10 tons per year of any one hazardous air pollutant (HAP), or at least 25 tons per year total of any HAPs. Major point sources include power plants; refineries; municipal waste incinerators; toxic waste transfer, storage and disposal facilities (TSDFs); TRI sources (facilities that are required to report their emissions under the Toxic Release Inventory program); and other sources that have reported emissions under other state and federal programs.

Area and Other Sources: These are small sources of air pollution which by themselves may not emit very much, but when their emissions are added together they may account for a sizable portion of the total emissions of air toxics. In NATA, USEPA refers to this category as "Area and Other Sources," and includes small industrial sources that fall below the "major source" threshold. Area sources are often too small or too numerous to be inventoried individually. The following are grouped under area sources in NATA:

     

  • Industrial processes such as chromium electroplating, surface coating of cans and paper, metal parts cleaning, metal recycling, small chemical manufacturing plants, and bakeries
  • Consumer products, such as personal care products, household products, adhesives and sealants, automotive products, and coatings such as paints.
  • Residential heating and fuel use
  • Pesticide use
  • Prescribed burns, and forest and wildfires, and structure fires
  • Gasoline stations
  • Dry cleaners
  • Institutional and commercial heating

Mobile Sources are divided into two categories:

     

  • On-road mobile sources are vehicles found on roads and highways, including cars, trucks, buses, and motorcycles.
  • Non-road mobile sources include aircraft, trains, lawnmowers, boats, dirt bikes, construction vehicles, farm equipment, etc.

BACKGROUND CONTRIBUTION

Some of the 33 air toxics evaluated in NATA are no longer emitted in significant quantities, but levels in air persist from past emissions. For a discussion of backround concentrations, click here.

"" 1990 Emissions Inventory Information

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